There is a great need for simple and inexpensive safety caps which are adaptable for mass production and which cannot be easily opened by children. A need for such a safety cap is extremely important for use with containers which contain harmful fluids such as charcoal lighter fluid, lye, paint remover, insecticides, toilet bowl cleaners, etc.
A very popular safety cap being presently used is of the type disclosed in U.S. Pat. No. 3,765,578 and U.S. Pat. No. 3,848,780. These caps depend upon registry of an external tab carried by the closure portion of the cap and an external interference lug carried by the dispensing portion of the cap. When the lug and the tab are in registration, the cap is so designed that removal of the closure portion of the cap is nearly impossible with the human hand. However, children will normally use any and all available means for opening containers. It has been found, since the tab and lug are external and exposed, that children may be able to open such caps by the utilization of a sharp object to pry the closure portion from the dispensing portion or by the utilization of their own teeth to accomplish this same purpose. The external interference lug-tab system is simply not sufficient to resist this type of attack by a child.
This deficiency of the above two type caps is well recognized and the solution thereof has been attempted. In U.S. Pat. No. 3,758,000 a cap is disclosed which is said to overcome the utilization of sharp objects or teeth in opening the caps. The type cap disclosed in this patent, however, requires a multistep procedure for opening and is very complex in design, thus rendering it unacceptable from a consumer standpoint and uneconomical from a production standpoint.
In U.S. Pat. No. 3,826,394 an assembly for keeping the child from using his teeth to remove the closing member from the dispensing member is disclosed. This assembly comprises a shield which will not allow the average child's mouth to come in contact with the closure member tab. Despite this advance in the art, it is clear to see that, with the interference lug-tab relationship still existing and external to the safety cap, a child may be able to still get a sharp object between the two and pry the cap to the open position.
Therefore it is an object of this invention to provide a safety cap which cannot be pried open when in the locked position. It is another object of this invention to provide a cap having an internal tamper-proof locking assembly.